Los Angeles daily herald., 1887-10-04
CYCLONES AND TORNADOKS.

CYCLONES AND TORNADOEs.
The Difference Between the Two
Atmespheric Currents.
In common speech, no difference is
recognized between these two classes
OF storms, but accurately speaking
they are essentially different. The
cyclone is an ocean storm. 1t has its
origin in the tropical seas OF both
hemispheres, and moves toward the
north. The entire body of wind, or
storm, has for its path parabolic
curve. The cyclones Of the Western
Hemisphere originate in the West In
dies. travel northwest until they
reach about thirty degrees latitude
north, then curve to the northeast,
and continue in that direction
sometimes at some distance Oft the
coast and sometimes on the shore,
finally trending oceanward and disap-
pearing in the vicinity of fifty degrees,
latitude north. The diameter of the
storm varies from several hundred to
over one thousand miles, and its
velocity is from sixty to eighty miles
an hour. At no point does the air
whirl in a circle, but there is ten
dency of the entire body of the storm
to revolve around the point of lowest
barometer. As rule the velocity of
the wind increases gradually till it
eliminates in fierce intensity
of movement that will wreck the
largest ships. In the actual center
of the storm there is dead calm.
Cyclones occur most frequently be-
tween August and November. In the
eastern hemisphere they form in the
vicinity of the Philippine islands,
moving thence northwestward to the
Asiatic coast, and then curving to the
northeast over the adjacent seas and
islands. They are there known as
typhoons. The origin in both hemi-
spheres can be placed at about ten to
twelve degrees north of the equator,
between the belt of calms and the
southern limit of the trade winds.
The tornado, on the other hand, is
always a land storm. Its motion is
always from southwest to northeast,
and its path varies from a few yards
to eighty rods in width. The moving
air always makes its appearance in
the form of a funnel-shaped cloud,
the small end drawing near to the
earth, and revolves about central,
vertical axis with inconceivable rapid
ity, and always in right to left di-
rection, or opposite to the movement
of the hands of a watch. With scarce
an exception, the tornado occurs in
the afternoon, just when the hottest
part of the day is over. 1t is caused
by heat, that is by the contact of cur
rents of low temperature from the
north with those of extremely high
temperature from the south.
The struggle of these atmospheric
forces toward an equilibrium of tenn
perature produces the mass of swiftly
Whirling air which we know as the
tornado cloud. The velocity Of the
particles of air in this mass is so great
that it is difficult to estimate it, but
it is believed to be from 100 to 500
miles an hour, and it is sometimes, no
doubt, even greater than this.
Observers note four motions of the
tornado cloud: l, the gyratory mo-
tion of its ar particles 2, the on
ward motion of the storm; 3, the
rising and falling movement of the
cloud, and 4. its oscillation or sway
ing from side to side. 1t is also stated
that the force of the tornado is con-
slant, that it does not seem to spend
itself, as the phrase is, by the destruc-
ton Of the strongest buildings, but the
cloud disappears by going from the
earth upward, evidently being &C ted
upon by forces in the upper regi ons
Of the atmosphere.
Close observation, such as has been
made of many tornadoes under the
direction of the signal service, seems
to show that electricity is not an ac-
tive cause of the tornado, but is often
present as an accompaniment, being
generated by the exceedingly rapid
motion of the air. Hail always ac-
companies the tornado, being formed
by the same cause, that is, the rapid
condensation of the moisture of the
southern winds by contact with
cold northern currents. Lightning
and thunder never attend on the tor
nado cloud itself, but sometimes ap-
pear in the region of other outside
clouds, while the tornado cloud is in
motion.
To conclude, we quote from the re-
Gently published work of Lieutenant
Finley Of the Signal Service on "Tor-
Aadoes, TO which We are indebted
for the facts summarized above-the
following description of the formation
Of . tornado cloud. Two currents of
air approaching each other from oppo-
site points will not come directly to-
gether, because of the influence Of the
relative motion of the earth. The
mass Of air coming from the south
would have . greater velocity than
that coming from the north. Therefore,
instead of meeting each other in
q direct line, the two currents will
from an angle at their intersection,
aad the combination of the two
masses will give rise to rotation in
direction contrary to the hands of a
watch. with its face upward. These
account for the spiral
of the air currents and the
formation of the vortex in the tornado.
The cold air from the northward will
lnderrun the warmer air from the
because Of the difference
n the density of the two masses, and
.s result will aid in the formation of
he whirl. ."[-Chicago Inter Ocean.